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Zhenrong Zheng 《Optik》2011,122(2):145-149
In this paper, an off-axis reflective projection lens with single Fresnel reflective surface and three aspheric surfaces were designed. The design method of reflective lens using spherical Fresnel surface is discussed. The MTF (Modulation Transfer Function) of the off-axis reflective lens, with optical magnification 100×, F-number 2.5 and field of view 120°, is over 40% at 0.6 lp/mm on the image side, the distortion is less than 2%. This design method can provide reference for application of Fresnel surface in wide field of view imaging, and possesses a bright future with the continuous development of fabrication technique. 相似文献
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A novel see-through display with a liquid crystal lens array was proposed.A liquid crystal Fresnel lens display(LCFLD) with a holographic screen was demonstrated.The proposed display system has high efficiency,simple fabrication,and low manufacturing cost due to the absence of a polarizer and color filter. 相似文献
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用菲涅耳衍射理论分析双光栅成像效应 总被引:7,自引:0,他引:7
从理论上对双光栅成像效应现象进行研究,分别从菲涅耳衍射理论和平面透射光栅的菲涅耳衍射公式出发,分析了物光波经过两个平行放置的平面透射光栅组成的系统衍射后的复振幅分布。分析结果表明,在理想状态下,当两个光栅的放置位置满足一定条件时,在第二个光栅后面可以观察到一个清晰的原物体图像。理论分析解释了两个光栅在双光栅成像效应中的作用,得到了双光栅成像效应发生时,两个光栅的空间频率、衍射光级数以及光栅放置位置之间的关系式,这与实验所得结果相一致。 相似文献
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QIAO DongHai LI ShunZhou & WANG ChengHao Institute of Acoustics Chinese Academy of Sciences Beijing China 《中国科学G辑(英文版)》2007,50(1):41-52
The acoustic field distributions and the convergent beams generated by the planar-structure Fresnel zone transducers on solid surface are investigated. Because only 0 and 180 degree phase transducers are used, an imaging system with the Fresnel zoom lens could work at very high frequency, which overcomes the frequency limit of the traditional phased array acoustic imaging system. Simulation results are given to illustrate the acoustic field distributions along the focal axis and the whole plane as well. Based on the principle of scanning of the focus with the change of frequency for the excited signal, an experimental imaging system is also built. Acoustic Fresnel zone transducers are fabricated at center frequency of 400 MHz. Measurements and detections of the known hole flaws at different depths of the fused quartz sample are presented to show that the imaging system with Fresnel zoom lens could move its focus by only changing the frequency of the excited signal. 相似文献
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X射线Bragg-Fresnel元件是近十年发展起来的一种用于X射线波段的新型光学元件。本文介绍一种具有二维聚焦效能的Bragg-Fresnel元件的设计理论和方法。设计中采用衍射理论并用C语言编制计算机程序系统对衍射图形进行设计。对于使用波长13.8nm,入射角5°,使用焦距200mm的使用条件,设计结果为35Mo/Si双层多层膜,周期厚度7.14nm,理论反射率约为60%;衍射图形共400个环带,最内环半宽度52.5μm,最外环宽度1.3μm。 相似文献
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高衍射效率闪耀全息透镜 总被引:1,自引:0,他引:1
提出一种制作位相全息透镜-闪耀全息透镜新设计,利用它可使位相全息透镜的位相分布类似位相菲涅耳透镜,其衍射效率理论值可达95%以上,但其制作过程要比位相菲涅耳透镜容易,文中给出了原理分析和实验验证,初步结果是令人满意的。 相似文献
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基于光学菲涅耳衍射的"盲数字水印"技术 总被引:3,自引:0,他引:3
基于光学菲涅耳衍射,设计了一种新的“盲数字水印”计算方法。水印图像通过离散菲涅耳衍射变换成一复矩阵,将此复矩阵的实部和虚部分开,分别嵌入到宿主图像的不同位置中。通过将水印嵌入点的宿主图像的像素值更改为其近邻像素值的均值,而实现“盲水印”的提取。数值计算结果表明:该水印计算法对像素变换攻击具有很强的鲁棒性,如图像亮度、对比度和灰度曲线的调整;能抵抗JPEG有损压缩、剪切和噪声污染攻击;能抵抗对图像的重采样攻击,可从显示屏幕拷贝的图像中提取水印。由于该方法为使用者提供了灵活的水印嵌入方式和双重密钥的选取,以及提取水印不需要原始图像数据,因而使该方法具有很高的安全性和实用价值。 相似文献
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Fresnel biprism is a one dimensional refractive element that has a lateral linear phase. Having been considered this element as a refractive axicon, its focal depth was evaluated theoretically and experimentally by means of Fresnel–Kirchhoff integral. It is shown that its focal length is a function of its refractive index and its apex angle. Experimental results are in very good agreement with theoretical work. 相似文献
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In this paper, we design a single concentrator to homogenize and concentrate the solar energy. The proposed concentrator only consisted of an array of refraction prisms. In order to homogenize the irradiance, all pitches of the Fresnel concentrator focus on the different position of the receiver. Finally, the Fresnel lens that achieves the uniformity of U is 14.6. An acceptance angle of 0.305° is achieved without using additional secondary optics. Full Width at Half Maximum (FWHM) of illumination distribution is 1.4 mm. 相似文献
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H.G. Kraus 《Optics & Laser Technology》1993,25(3)
Derivation and applications of the characteristics optical pathlength Fresnel number equation for spherical waves focused by an ‘ideal’ circular lens illustrate the wealth of information which is quickly available from its use. A Kirchhoff wavefront diffraction formulation of this problem is developed and used to aid in this analysis. New characteristics about the diffraction field are revealed. 相似文献
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The intensity distribution in Fresnel diffraction through a slit includes numerous small fluctuations referred to as ripples. These ripples make the modelling of the intensity distribution complicated. In this study, we examine the characteristics of the Fresnel diffraction intensity distribution to deduce the rule for the peak position and then propose two types of quantum-mathematical models to obtain the distance between the edge and the peak point. The analysis and simulation indicate that the error in the models is below 0.50 μm. The models can also be used to detect the edges of a diffraction object, and we conduct several experiments to measure the slit width. The experimental results reveal that the repetition accuracy of the method can reach 0.23 μm. 相似文献
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We show that layers of acousto-optic gyrotropic paratellurite crystals perturbed by ultrasound can be used as efficient light
modulators in transmission and reflection mode. We have established that the relative intensities of the diffracted waves
are determined by the ratio of the refractive indices of the bounding media, the intensity of the ultrasound, and the thickness
of the modulated layer. We show that for an asymmetric diffraction structure, efficient acousto-optic conversion is possible
in reflection mode, and the weak effect of the gyrotropy is due to its suppression by Fresnel reflection at the boundaries
of the layer.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 819–823, November–December, 2006. 相似文献